Flat roof drainage problem needing solving

[pilsbury]

Now you could accuse me of making this extension up as I go along...... As a first timer it was pretty well planned out, a few minor details I was unsure of were left to "work it out" when I got there! Well, now I am there about to start the roof.

The diagram included shows my conundrum fairly well. How do I drain the water off the roof?

The main house is to the left of this diagram. The large pitched roof at the rear is the original kitchen. The flat roof to the front left is the original garage flat roof with red arrows showing fall. The joists, original, are actually cut for the fall. ( I shall be replacing deck, insulating and covering with GRP). The rest to the right, front to back is the new extension. I shall be putting a tiled monopitch all the way round to hide the flat roof to be in keeping with the rest of the house. This elaborate effort has to be done as I have a large stained glass window on the landing above the garage roof. To the far right (not shown) is an original wall framing the extension and extends up to the ridge of the monopitch roofs.

So basically in this diagram, I'm creating a nice big paddling pool. How do you suggest I get the water off the roof? My thoughts were to have a gulley or two coming out through the monopitch roof at some point. To add to the difficulty, the extension flat roof is approx 250mm higher than the garage flat roof (marked by the bent arrow). This leads me to think the fall of the extension roof should lead towards the garage..... and then drain away from there .....somehow....

 

[^woody^]

Is that one of those impossible Escher pictures?

 

[freddiemercurystwin]

This should all of been thought about before you even dug the trenches! Got a different view of that roof? Looks like it was designed by Stevie Wonder.

 

[pilsbury]

Well Stevie Wonder did help with the blockwork. Don't believe me? Come and take a look - all the proof you need! Yes I am aware of all the should of's.... Main one being, should have got an architech, builder, plumber, roofer, project manager.... Doing it all on my ownsome purely for financial reasons.

Here are a couple of other views as requested. You can tell I'm no sketchup master.... nor master builder/roofer etc etc.

Front elevation - Main house to the right, brick wall to the left

Rear elevation - new monopitch has to be max ridge of 4m

Side elevation - main house is attached here with big landing window over garage flat roof hence elaborate roof design

 

[pilsbury]

Here is a current photo.

 

[^woody^]

I need to have a lay down first.

 

[pilsbury]

And a stiff drink.

 

[freddiemercurystwin]

Hmm let the pills kick in too.

 

[Nige F]

Is that 54a on the right ?

 

[pilsbury]

Is that 54a on the right ?

No. Normal numbers.

 

[pilsbury]

Anyone had a chance to think of any suggestions? - no matter how small. I've still got my initial idea but as I've never done it before any bouncing of ideas may avoid some pitfalls.

 

[datarebal]

well you cant make the water run up hill.. so there's a start

 

[freddiemercurystwin]

I've looked at all the images and the photo, I don't know what's existing, what's new and which property is yours in the photo, maybe some better existing and proposed images would help. Did you come up with this bastardized 'design' to keep it PD? Because if ever there was an reason as to why PD doesn't work this is it. I guess you expect to die before you ever need to sell?

 

[pilsbury]

I've looked at all the images and the photo, I don't know what's existing, what's new and which property is yours in the photo, maybe some better existing and proposed images would help. Did you come up with this bastardized 'design' to keep it PD? Because if ever there was an reason as to why PD doesn't work this is it. I guess you expect to die before you ever need to sell?

I do enjoy your thoughts! I shall post some more images tomorrow after work. My property is to the left. The house on the right is my neighbours. The wall separating the properties is mine and is not attached to next door but forms the wall of my extension. The reason for the "design" is to avoid a flat roof on show. By adding the tiled mono pitch roof around the garage and onto the extension hides both the existing garage flat roof and the new extension flat roof. I very much like that idea. Not a fan of flat roof look.

As for doing this as PD, I felt it all that was necessary. But I did consider what planning permission would give me. To make the roof as simple as possible, I could have removed the existing kitchen roof and put a pitched roof over the entire lot - old kitchen, garage, extension..... But this would have lost the landing window which for me was a big no.

Do I expect to die before sale? Who knows, but I do hope it doesn't turn out to be the monstrosity you're suggesting..... It looks good in my head - desperately trying to turn it into that.

 

[Nige F]

I can see your idea of "tunnels" through the pitch to shed water ( having made them in lead) - but a fibreglass roof would be problematic